This invention relates to an improvement in a suction-type liquid measuring equipment, and especially to a structure of inlet/outlet for allowing a liquid to come in and out.
In case for example when casting a cast product, a molten metal of such as aluminum alloy is conventionally filled in a cavity of metal mold. For this purpose, there is such a method that a molten metal accumulated in a metal melting/holding furnace is drawn up by a ladle and filled in the cavity of metal mold. (Refer to Published Japanese Utility Model Application (KOKAI) No. 3-111447 and Published Japanese Patent Application (KOKAI) No. 4-9262, for example.)
There is another method in which a ladle provided with an intake port provided at its bottom face is dipped in a molten metal to take the molten metal in the ladle, so that the ladle is moved to the metal mold under a condition where the above intake port is closed by a stopper. Then, the stopper is removed to fill the molten metal into the cavity of metal mold.
There is further another method, as shown in FIG. 6, in which a sealed-type ladle A sealed at its top opened portion of the ladle body B with a cover K is used, and an inlet/outlet pipe C protruding down straight from a bottom face of the ladle body B of the ladle A is dipped in the molten metal. Under this state, an inside of the ladle body B is evacuated and brought to a negative pressure by way of a suction pipe D protruding upward from the cover K, so as to suck a molten metal E from the inlet/outlet pipe C. Thus, the negative pressure in the ladle body B is made balance with a gravity of the molten metal E, and the molten metal E is measured and held at a constant volume in the ladle body B. Thereafter, the ladle A is transferred to the metal mold and the negative pressure in the ladle body B is released, so as to fill the molten metal E in the cavity of metal mold.
In the above-mentioned first and second methods, however, the holding volume of molten metal differs depending on the way of dipping of the ladle. Therefore, the molten metal can not be filled in the cavity of metal mold neither too much nor too less.
In the third method, the holding volume of molten metal can be made constant by controlling the negative pressure in the ladle body B to a specified value. However, when the negative pressure in the ladle body B is fluctuated due to an occurrence of disturbance, the balance between the negative pressure in the ladle body B and the gravity of the molten metal E is destroyed, so that the molten metal E can not be measured and held in the ladle body B at a constant volume and the molten metal E becomes unable to be fed in the cavity of metal mold neither too much nor too less as in case of the foregoing two examples. Especially, in case when the negative pressure in the ladle body B increases, a molten metal level forming an upper surface of the molten metal E rises up to a level higher than that of the molten metal shown at a left side of FIG. 6, which existed before the disturbance occurred. (A rising-up height is shown using a symbol H at right side of FIG. 6.) A lower surface of the molten metal E rising up accompanied by the upper surface also rises up to a level higher than that of the molten metal shown at left side of FIG. 6, which existed before the disturbance occurred. (A rising-up height is shown using a symbol I at right side of FIG. 6). However, since the inside diameter of the ladle body B is by far larger than that of the inlet/outlet pipe C, a rising-up height of the molten metal (upper surface) is smaller than that of the lower surface and the height of range of the molten metal E becomes small by a height (I-H) as compared with the case before the occurrence of disturbance. The height of range of the molten metal E existing before the occurrence of disturbance is shown at left side of FIG. 6 using a symbol F, and the height of range of the molten metal E existing after the occurrence of disturbance is shown at right side of FIG. 6 using a symbol G. As the result, an unbalance between the negative pressure in the ladle body B and the gravity of the molten metal E enhanced. Accordingly, air is sucked from the inlet/outlet pipe C so that air bubbles J occur and a trouble such as a formation of oxidized film is brought about.
Measuring a liquid with good precision is utilized and applied not only to the case where the molten metal is measured in the casting work, but also to all cases where liquids other than the molten metal are measured.
This invention is made in consideration of the above point, and an object of it is to always measure and hold securely a liquid such as the molten metal at a constant volume in a vessel such as the ladle etc., without being affected by an increase in a negative pressure (suction force) caused by an occurrence of disturbance.